All Questions
62
questions
-3
votes
0
answers
70
views
Please tell me about "Action at a distance" in Electrodynamics [closed]
I am confused about how test charge informed about source charge. So I research on it. Web said me that it is "Action at a distance phenomenon". What is this? I am a first year Undergraduate ...
0
votes
1
answer
60
views
How is information defined when considering locality in quantum mechanics?
$\newcommand{\ket}[1]{|#1\rangle}$
My question is a follow-up from this discussion about the presence of non-local correlations in a theory that is deemed local. The first answer talks about the ...
0
votes
0
answers
62
views
Can you model relativistic interactions without locality?
Assume $c=1$
I've been doing relativity by myself so I may be making some assumptions here that I would not have if my learning had been more extensive.
One such assumption is that you can model the ...
- 312
1
vote
2
answers
126
views
On the notion of Local Causality
In 1976, John Bell proved that any locally causal theory can't account for certain observed correlations, he formulated the local causality hypotesis in terms of "local beables".
In ...
- 407
2
votes
1
answer
89
views
How to interpret Poisson bracket of fields in terms of causality?
In quantum field theory, the fact that space-like separated observables commute, i.e. $[\hat {\phi (x)}, \hat{\phi(y)}]=0$, is taken as the test for causality. The equivalent statement for classical ...
- 519
0
votes
1
answer
148
views
Newton's second law - local laws and non-local laws
What are local laws? I was reading this line in a book...
Newtons second law is a local law. This means that it applies to a particle at a particular instant without taking into consideration any ...
- 13
2
votes
2
answers
96
views
Is Gauss law for gravity local?
in Newtonian gravity, the gravitational field obeys the equation
$$\nabla^2 \phi = 4 \pi G \rho$$
David Tong in his notes on general relativity claims that this equation works well when $\rho$ is not ...
- 1,931
0
votes
1
answer
415
views
How does the many-worlds interpretation solve spooky action at a distance?
If we take the classic example of two particles that are entangled with up spin and down spin, and we separate these particles a few light years apart and then observe them one after the other, they ...
2
votes
1
answer
148
views
Is there something that violates "time locality"?
The way I understand locality is that for an object to influence another object away from it, it has to do so through the space that separates them. It can shoot out an EM wave to the other object, ...
1
vote
0
answers
91
views
Is causality a consequence or a constraint in physics?
I wonder if causality is a constraint that we must add to physical models (if needed), or is it a consequence of Lorentz invariance and locality (or something else). In other words, which properties ...
- 595
1
vote
0
answers
140
views
Local algebra of AQFT vs Bisognano Wichmann Theorem
Maybe I am misunderstanding something really stupid, but I am finding it hard to think of local algebras in terms of wedge algebras. One of the claims (see, e.g., Section 3 and 4 of this paper) is ...
0
votes
0
answers
115
views
How do Lieb-Robinson Bounds talk about locality without the position operator?
So we know when one goes from QM to QFT Lieb Robinson bounds become micro causality. But micro causality is a statement on the commutators assuming they are space-like, time-like or light-like. ...
- 1,389
2
votes
2
answers
193
views
Global conservation + Lorentz invariance = local conservation?
On the page 83 of "Quantum Field Theory Lectures of Sidney Coleman", Coleman showed an interesting example:
It seems that global conservation law and local conservation law can be related. ...
- 192
2
votes
1
answer
161
views
Thought experiment in relativistic quantum mechanics?
Background
Consider the following thought experiment in the setting of relativistic quantum mechanics (not QFT). I have a particle in superposition of the position basis:
$$ H | \psi \rangle = E | \...
- 1,389
-2
votes
1
answer
292
views
What does it mean that gravity is '"local"? [closed]
What is "local" defined to be? Why don't larger systems affect smaller ones? ie. Don't we need to consider the gravitational pull from all other objects in the universe? Is this "...
- 167